RNA extraction
One ml RNAiso plus reagent (Takara, Dalian, China) was added to cells on 100mm Petri dish. Cell lysates were collected and incubated at room temperature for 5min. Cells were then centrifuged at 13500 ×g for 5min at 4°C. A 200μL of CHCl3 was added, followed by 30sec mixing and 5min incubation at RT, samples were centrifuged at 13500 ×g for 15min at 4°C to separate RNA into aqueous phase. Aqueous phase (about 600ul) was transferred to a new tube and RNA was precipitated with 750 μL of absolute isopropanol at RT for 10min and then centrifuged at 13500 ×g for 10min at 4°C. Precipitate was washed with 1mL 70% ethanol, followed by centrifugation at 13500 ×g for 5min at 4°C. RNA pellet was resuspended in 50μL of DEPC-treated water. RNA concentrations were determined using NanoDrop 2000 (Thermo Fisher Scientific, USA). RNA integrity was checked on 0.8% agarose gel.